I couldn't execute the join query for two datasources (which are actually mysql DBs).
logs in octopus.log are as follows.

2015-12-30 15:45:41,943 DEBUG kr.co.bitnine.octopus.engine.QueryEngine: FQN translated: SELECT ename, dname
FROM bb.sample.emp,
aa.sample.dept
WHERE emp.ename = dept.dname
2015-12-30 15:45:41,952 INFO kr.co.bitnine.octopus.engine.QueryEngine: Generated plan:
LogicalProject(ename=[$3], dname=[$10]): rowcount = 1500.0, cumulative cost = {13200.0 rows, 13202.0 cpu, 0.0 io}, id = 262
LogicalFilter(condition=[=($3, $10)]): rowcount = 1500.0, cumulative cost = {11700.0 rows, 10202.0 cpu, 0.0 io}, id = 261
LogicalJoin(condition=[true], joinType=[inner]): rowcount = 10000.0, cumulative cost = {10200.0 rows, 202.0 cpu, 0.0 io}, id = 260
JdbcTableScan(table=[[bb, sample, emp]]): rowcount = 100.0, cumulative cost = {100.0 rows, 101.0 cpu, 0.0 io}, id = 258
JdbcTableScan(table=[[aa, sample, dept]]): rowcount = 100.0, cumulative cost = {100.0 rows, 101.0 cpu, 0.0 io}, id = 259

2015-12-30 15:45:41,953 DEBUG kr.co.bitnine.octopus.frame.Session: extended query sub-protocol message
2015-12-30 15:45:41,953 DEBUG kr.co.bitnine.octopus.frame.Session: handle Bind message (portal=, stmt=)
2015-12-30 15:45:41,953 DEBUG kr.co.bitnine.octopus.engine.QueryEngine: complex query: SELECT emp.ename, dept.dname
FROM bb.sample.emp AS emp,
aa.sample.dept AS dept
WHERE emp.ename = dept.dname
2015-12-30 15:45:41,953 INFO kr.co.bitnine.octopus.engine.QueryEngine: create portal '' for by-pass (session=1351644949)
2015-12-30 15:45:41,954 DEBUG kr.co.bitnine.octopus.frame.Session: extended query sub-protocol message
2015-12-30 15:45:41,954 DEBUG kr.co.bitnine.octopus.frame.Session: handle Describe message (type='P', name=)
2015-12-30 15:45:41,954 INFO kr.co.bitnine.octopus.engine.CursorByPass: Avatica JDBC connection for session(1351644949)
2015-12-30 15:45:42,107 DEBUG kr.co.bitnine.octopus.engine.CursorByPass: execute CursorByPass (rows=0)
2015-12-30 15:45:42,115 INFO kr.co.bitnine.octopus.engine.CursorByPass: return connection to "null" for session(1351644949)
2015-12-30 15:45:42,115 ERROR kr.co.bitnine.octopus.frame.Session: kr.co.bitnine.octopus.frame.OctopusException: failed to execute by-pass query: null
at kr.co.bitnine.octopus.frame.Session.handleDescribe(Session.java:758)
at kr.co.bitnine.octopus.frame.Session.messageLoop(Session.java:367)
at kr.co.bitnine.octopus.frame.Session.run(Session.java:114)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Caused by: kr.co.bitnine.octopus.postgres.utils.PostgresException: failed to execute by-pass query: null
at kr.co.bitnine.octopus.engine.CursorByPass.execute(CursorByPass.java:253)
at kr.co.bitnine.octopus.engine.CursorByPass.describe(CursorByPass.java:260)
at kr.co.bitnine.octopus.frame.Session.handleDescribe(Session.java:739)
... 5 more
Caused by: java.sql.SQLException
at org.apache.calcite.avatica.Helper.createException(Helper.java:52)
at org.apache.calcite.avatica.Helper.createException(Helper.java:41)
at org.apache.calcite.avatica.AvaticaConnection.executeQueryInternal(AvaticaConnection.java:473)
at org.apache.calcite.avatica.AvaticaPreparedStatement.executeQuery(AvaticaPreparedStatement.java:111)
at kr.co.bitnine.octopus.engine.CursorByPass.execute(CursorByPass.java:224)
... 7 more
Caused by: java.lang.NumberFormatException
at java.math.BigDecimal.(BigDecimal.java:470)
at java.math.BigDecimal.(BigDecimal.java:739)
at org.mariadb.jdbc.internal.common.AbstractValueObject.getInt(AbstractValueObject.java:111)
at org.mariadb.jdbc.MySQLResultSet.getInt(MySQLResultSet.java:135)
at org.apache.commons.dbcp2.DelegatingResultSet.getInt(DelegatingResultSet.java:215)
at org.apache.commons.dbcp2.DelegatingResultSet.getInt(DelegatingResultSet.java:215)
at Baz$1$1$1$1.apply(Unknown Source)
at org.apache.calcite.runtime.ResultSetEnumerable$ResultSetEnumerator.current(ResultSetEnumerable.java:182)
at Baz$1$1.current(Unknown Source)
at org.apache.calcite.linq4j.EnumerableDefaults.toLookup_(EnumerableDefaults.java:2579)
at org.apache.calcite.linq4j.EnumerableDefaults.toLookup(EnumerableDefaults.java:2570)
at org.apache.calcite.linq4j.EnumerableDefaults.toLookup(EnumerableDefaults.java:2546)
at org.apache.calcite.linq4j.DefaultEnumerable.toLookup(DefaultEnumerable.java:701)
at org.apache.calcite.linq4j.EnumerableDefaults$10.enumerator(EnumerableDefaults.java:1086)
at org.apache.calcite.linq4j.AbstractEnumerable.iterator(AbstractEnumerable.java:33)
at kr.co.bitnine.octopus.engine.calcite.CalciteMetaImpl.execute(CalciteMetaImpl.java:628)
at org.apache.calcite.avatica.AvaticaConnection.executeQueryInternal(AvaticaConnection.java:463)
... 9 more

Similary, I failed to run a testcase for join query (SessionServerTest#testComplexSelect)

2015-12-30 16:12:38,118 INFO engine.QueryEngine (QueryEngine.java:processBind(334)) - create portal '' for by-pass (session=1079759576)
2015-12-30 16:12:38,125 INFO engine.CursorByPass (CursorByPass.java:prepareStatement(106)) - Avatica JDBC connection for session(1079759576)

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data.__DEFAULT.employee
employee

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SELECT id, name
FROM employee
SELECT id, name
FROM employee

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DATA2.__DEFAULT.TMP2
TMP2
2015-12-30 16:12:38,677 INFO engine.CursorByPass (CursorByPass.java:execute(233)) - JDBC type of column 'name' is 12
2015-12-30 16:12:38,678 INFO frame.Session (Session.java:handleExecute(645)) - run portal ''
2015-12-30 16:12:38,681 ERROR frame.Session (Session.java:run(117)) - java.lang.UnsupportedOperationException
at org.apache.calcite.avatica.AvaticaResultSet.cancel(AvaticaResultSet.java:171)
at org.apache.calcite.avatica.AvaticaStatement.cancel(AvaticaStatement.java:299)
at kr.co.bitnine.octopus.engine.CursorByPass.close(CursorByPass.java:288)
at kr.co.bitnine.octopus.frame.Session.handleExecute(Session.java:661)
at kr.co.bitnine.octopus.frame.Session.messageLoop(Session.java:361)
at kr.co.bitnine.octopus.frame.Session.run(Session.java:114)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

2015-12-30 16:12:38,681 INFO engine.CursorByPass (CursorByPass.java:close(300)) - return connection to "null" for session(1079759576)